VEGF expression is higher than CD31 at biopsy, suggesting that VEGF is a more objective and sensitive marker of angiogenic regulation; it can therefore be used to evaluate the prognostic role of angiogenesis in osteosarcoma, as well as in other carcinomas and mesenchymal tumors [12,18,19,22,25,26]. Here, PECAM1 is linked to osteosarcoma.